He was found alive, trying to load his musket to fight again.

From Ages of Revolution: How Old Were They on July 4, 1776? by Todd Andrlik. Ages of some of the Founding Fathers at the time of the Declaration of Independence. As Andrik points out, a couple of them might have been better called Founding Teenagers. You can look at the list and see a divine hand, or wonder at the circumstances that led to such a concentration of talent and ability at such a time. Alternatively, you can look at the list and think, "What a bunch of curve busters".

In particular, look at the ages of the three authors of The Federalist Papers, Alexander Hamilton, James Madison and John Jay, 21, 25, and 30 at the time of the Declaration of Independence (The Federalist Papers were penned in 1787-88 in support of the ratification of the Constitution). The education system might not have existed at that time but there was a phenomenal degree of self-education going on.

Marquis de Lafayette, 18
James Monroe, 18
Henry Lee III, 20
Aaron Burr, 20
John Marshall, 20
Nathan Hale, 21
Alexander Hamilton, 21
Gouveneur Morris, 24
Betsy Ross, 24 ad
James Madison, 25
Henry Knox, 25
Edward Rutledge, 26
John Paul Jones, 28
John Jay, 30
Abigail Adams, 31
Casimir Pulaski, 31
Nathanael Greene, 33
Thomas Jefferson, 33
Benedict Arnold, 35
Thomas Knowlton, 35
Ethan Allen, 38
Thomas Paine, 39
Patrick Henry, 40
John Adams, 40
Daniel Boone, 41
Francis Lightfoot Lee, 41
Paul Revere, 41
Charles Lee, 44
Francis Marion, 44
George Washington, 44
Friedrich von Steuben, 45
Martha Washington, 45
Benjamin Harrison, 50
Samuel Adams, 53
Thomas Gage, 56
Israel Putnam, 58
Benjamin Franklin, 70
Samuel Whittemore, 81

Samuel Whittemore might not be widely remembered, but he is well worth remembering for his example of determined staunchness as recounted in Wikipedia.

On April 19, 1775, British forces were returning to Boston from the Battles of Lexington and Concord, the opening engagements of the war. On their march they were continually shot at by colonial militiamen.

Whittemore was in his fields when he spotted an approaching British relief brigade under Earl Percy, sent to assist the retreat. Whittemore loaded his musket and ambushed the British from behind a nearby stone wall, killing one soldier. He then drew his dueling pistols and killed a grenadier and mortally wounded a second. By the time Whittemore had fired his third shot, a British detachment reached his position; Whittemore drew his sword and attacked. He was shot in the face, bayoneted thirteen times, and left for dead in a pool of blood. He was found alive, trying to load his musket to fight again. He was taken to Dr. Cotton Tufts of Medford, who perceived no hope for his survival. However, Whittemore lived another 18 years until dying of natural causes at the age of 98.